The present invention relates to an apparatus for preparing winding mandrels with corresponding tubular winding cores fitted on them for introduction into rewinding machines or other winding machines.
In various industrial sectors, for example in the paper converting industry, the textile industry and the production of nonwoven textiles, it is frequently necessary to wind on to rolls of smaller or larger diameter a web material taken from a reel of greater diameter. Frequently, a plurality of rolls of smaller height are formed simultaneously by winding strips of web material generated by longitudinally cutting a single strip taken from the reel of greater diameter. The strips are wound on tubular cores adjacent to each other and carried by an expanding winding mandrel. An example of a machine for carrying out this type of winding is described in EP-A-0747308.
In some cases, the rolls which are formed simultaneously on the cores fitted on to the mandrel have heights (in other words, axial lengths) which differ from each other. Usually, one or more operators prepare the tubular cores which have previously been cut from a continuous tube, fitting them on to one or more mandrels positioned outside the rewinding machine, and then, at the start of each winding cycle, insert the individual mandrels, fitted with the corresponding tubular cores, into the rewinding machine. This procedure is time-consuming, tiring, and labor-intensive.
Moreover, since the individual tubular cores fitted on each mandrel generally have different lengths from each other, errors may frequently occur as a result of the operator""s failure to fit the cores in the correct order. Consequently there will no longer be a match between the sequence of the axial lengths of the tubular cores and the sequence of the transverse widths of the strips of web material which are fed to the mandrel for winding.
Furthermore, when this conventional procedure for preparing the mandrels is followed, the various tubular cores fitted on them are necessarily adjacent to each other. This means that the individual rolls which are formed on the mandrel are also necessarily adjacent to each other. This causes considerable problems, since the windings of one roll may interfere with those of an adjacent roll, giving rise to difficulties in the subsequent separation. The necessity of winding rolls on cores adjacent to each other entails further problems in cases in which the wound material is subject to shrinkage in respect of its width. This is because in this case there is a risk that the tubular cores will project from one or both ends of the finished roll, giving rise to difficulties in the subsequent operations of handling the rolls.
At the present time, if shrinkage of the wound material occurs during the rewinding stage, then, in order to prevent the projection of the cores from the finished rolls, the operator inserts a spacer between each core and the next in such a way that the cores remain inside the roll in each case. These spacers are in the form of open rings, to allow them to be inserted even when the cores have already been fitted on to the mandrel. The spacers are usually made from plastic material and are recovered at the end of the rewinding stage after the mandrel has been extracted. This system is unsatisfactory in that it is complicated, labor-intensive, and a source of errors on the part of the operator.
In rewinding machines of the aforementioned type, a set of cutters is placed upstream of the winding area in order to divide the web material taken from the reel into strips of the desired width. A computerized system is normally used to position the individual cutters correctly with respect to the transverse direction of the web material. The tubular cores, however, are cut to size (with core lengths which must match the widths of the individual strips into which the cutters divide the web material) in a different area of the plant, with a consequent risk of failure of matching between the positions of the cutters which cut the web material in the longitudinal direction and the axial dimensions of the individual tubular cores.
The object of the present invention is to provide an apparatus or device which makes it possible to overcome the disadvantages, the limitations and the possibilities of error of the conventional systems.
More particularly, a first object of the present invention is to provide a device and a method which permit the fast and accurate preparation of the mandrels with the corresponding tubular cores fitted on them for subsequent introduction into the rewinding machine.
A further object of the present invention is to provide a device and a method which make it possible to reduce the labor-intensiveness of cycles of winding or rewinding web materials.
Yet another object of the present invention is to provide a device and a method which make it possible to reduce or eliminate errors in the preparation of the mandrels for winding.
The object of an improved embodiment of the invention is to provide a method and a device which make it possible to automate the operations of preparing the cores and coordinating the cutting of the cores with the cutting of the web material, to achieve greater precision and speed.
An object of the present invention is also to provide a method and a device which avoid the disadvantages which are found in the rewinding of web materials which tend to shrink in the transverse direction, and also the problems arising from the difficulties of detaching rolls wound on adjacent cores carried by a single mandrel.
These and other objects and advantages, which the following text will make clear to those skilled in the art, are essentially achieved with a device comprising, in combination, an extraction station with an extractor mechanism for extracting a mandrel from one or more rolls of web material which has previously been wound and for inserting the extracted mandrel into a tube or core of cardboard or the like; a cutting station with cutting means for cutting the tube fitted on the mandrel, transforming it into a set of tubular cores aligned on the mandrel; and an insertion station with insertion members for inserting the mandrel with the tubular cores fitted on it into a rewinding machine or other winding machine.
These three stations enable the operations of preparing the tubular cores on the mandrel to be carried out in a partially or completely automatic way.
In the preferred embodiment of the invention, the three aforementioned stations are distributed spatially along a path which extends in a direction preferably orthogonal to the axis of the mandrel. This is particularly advantageous since it simplifies the design of the device and makes it possible to move the mandrel, while the tubular cores are being prepared on it, from the extraction position to the position of reinsertion into the rewinding machine, said two positions being normally spaced apart because of the presence of the winding members in an intermediate position. The use of three stations spaced apart also yields the advantage that it is possible to handle three mandrels simultaneously, one in the extraction station, one in the cutting station and the third in the insertion station.
On the other hand, the location of a plurality of stations, particularly two stations, in the same position in space is not excluded. For example, the cutting station can be spatially superimposed on or coincident with the extraction station, or the cutting station can be spatially coincident with or superimposed on the insertion station.
In a particularly advantageous embodiment of the invention, the extractor mechanism causes, by a single movement, the extraction of the mandrel from the finished roll or rolls and its insertion into the tube. On the other hand, the extraction from the finished roll or rolls and the insertion into a new tube by two separate movements is not excluded.
The extractor mechanism can be made with a pair of shaped wheels or rollers which are pressed against the outer surface of the mandrel and then made to rotate. Other systems of extracting the mandrel, for example by means of a pneumatic or hydraulic cylinder or the like, are not excluded. The use of powered shaped rollers makes the device particularly simple, economical and reliable, and also versatile in that it is easily adaptable to different mandrel diameters. It makes it particularly simple to insert the mandrel into a new tube at the same time as it is extracted from the finished roll.
Preferably, the mandrel used is of the expanding type, which is deflated before the extraction from the roll and re-inflated or expanded once it has been inserted into the tube. For this purpose, the extraction station comprises known means for deflating and inflating the mandrel.
In an advantageous embodiment, the extractor mechanism comprises a pair of shaped rollers which are pressed against the mandrel and made to rotate to move said mandrel in a direction parallel to its axis. This mechanism is particularly simple and enables the mandrel to be extracted and inserted into the tube efficiently, with a single movement. The shaped rollers can both be powered, but having one of them idle is not excluded.
A device for supporting the mandrels can advantageously be provided at the extraction station. In a possible embodiment, usable especially for long mandrels, the support device consists of a tube support cradle, made for example in the form of a roller train, a V-shaped section or the like. The support device, for example the aforesaid roller train, can be vertically movable so that it can be brought to a lower loading position, where it is easier to introduce the tube, and from there to an upper position for the insertion of the mandrel into the tube. The height of the second position is determined by the structure and size of the rewinding machine with which the device is associated. Advantageously, the positioning movement can be obtained by means of a gantry system with slides which move vertically along the uprights.
When the three stations, for extraction, cutting and insertion, are positioned so that they are separated from each other in space, means of transferring the mandrel from one to another will be provided. In a simple and economical embodiment, the transfer is carried out by rolling on inclined planes or rolling chutes. Suitable expulsion means, which push the mandrel, with the tube or tubular cores fitted on it, on to the corresponding inclined plane, are provided at the extraction station and/or at the cutting station.
The cutting station can comprise, in a possible embodiment, a pair of cylinders forming a cradle which supports the mandrel with the tube fitted on it for subsequent cutting into tubular cores. The rotation of the cylinders causes the mandrel supported on them to rotate correspondingly about its own axis. The possibility of imparting the rotary motion to the mandrel by other means, for example by means of a system of powered centers, is not excluded. The preferred system, with the pair of cylinders, is simpler in terms of construction and less critical in respect of tolerances.
The cutting station comprises one or more cutting heads, which in the preferred embodiment are located above the pair of cylinders, and each of which carries a cutting tool, preferably consisting of a discoid blade. The latter is preferably a smooth-edged blade and is idly supported.
The cutting tool is advantageously carried by an oscillating arm which controls its movements toward and away from the mandrel, although the possibility of using mechanisms of another type for moving the cutting tools toward and away from the mandrel is not excluded. The use of an oscillating arm is particularly advantageous in terms of mechanical simplicity. Additionally, in this way it is easy to provide a system of stops which define the operating position, in other words a plurality of operating positions of the tools, which can be selected alternatively according to the diameter of the mandrel and therefore of the tube to be cut.
Further advantageous characteristics and embodiments of the device according to the invention are described in the attached dependent claims.
The method according to the invention comprises the stages of extracting a mandrel from a roll or from a plurality of rolls formed in a rewinding machine or other; inserting the mandrel into a tube and fixing the tube with respect to the mandrel; cutting the tube fitted on the mandrel into a plurality of tubular cores aligned along said mandrel; and inserting the mandrel with the tubular cores fixed on it into a rewinding machine or other winding machine for the formation of rolls of web material on the individual cores.
In a particularly advantageous embodiment of the method according to the present invention, the mandrel is simultaneously extracted from the roll or rolls and inserted into the tube. Further advantageous characteristics of the method according to the invention are indicated, in the attached claims.